single-shot T.C. barrel specification

[Bigger is Better]

I have a doubt, guys: the length of a Thompson Center barrel - Contender and Encore, pistol and rifle - is calculated from the point which we insert the cartidge in, or from the end of the bullet inserted in. In other words, if it is like I think, the real length of a .45-70 (for example) Contender barrel is 15" minus 2.550" (45-70 cartridge length), so about 12.5". Correct?
Or the 15 inches of the barrel are all crossed by the bullet, so total barrel length is 15" plus cartridge length?
I hope you've understood, 'cause I'm not be able to explain it better. Sorry

 

[MMCSRET]

It is the outside overall length of the barrel dismounted from the frame.

 

[wdlsguy]

Here is how the U.S. government measures barrel length:

the length of the barrel having an integral chamber(s) on a shotgun or rifle shall be determined by measuring the distance between the muzzle and the face of the bolt, breech, or breech block when closed and when the shotgun or rifle is cocked.

27 CFR 479.11

 

[grendelbane]

Barrel length means different things to different people. As mentioned, the US gov't has one way to measure a barrel, and ballisticians have another way.

They measure barrel length from the base of the bullet, so the barrel length may change with different loads.

One way to look at this is as the useable barrel length. In revolvers, this takes into account the cylinder.

The gov't, and most people, are going to consider the barrel length to be the distance from the muzzle to the breech face, except for revolvers, which are measured without including the cylinder.